Diff: targets/TARGET_NXP/TARGET_LPC176X/analogin_api.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC176X/analogin_api.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,125 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "mbed_assert.h"
+#include "analogin_api.h"
+
+#include "cmsis.h"
+#include "pinmap.h"
+
+#define ANALOGIN_MEDIAN_FILTER      1
+
+#define ADC_10BIT_RANGE             0x3FF
+#define ADC_12BIT_RANGE             0xFFF
+
+static inline int div_round_up(int x, int y) {
+  return (x + (y - 1)) / y;
+}
+
+static const PinMap PinMap_ADC[] = {
+    {P0_23, ADC0_0, 1},
+    {P0_24, ADC0_1, 1},
+    {P0_25, ADC0_2, 1},
+    {P0_26, ADC0_3, 1},
+    {P1_30, ADC0_4, 3},
+    {P1_31, ADC0_5, 3},
+    {P0_2,  ADC0_7, 2},
+    {P0_3,  ADC0_6, 2},
+    {NC,    NC,     0}
+};
+
+#define ADC_RANGE    ADC_12BIT_RANGE
+
+void analogin_init(analogin_t *obj, PinName pin) {
+    obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
+    MBED_ASSERT(obj->adc != (ADCName)NC);
+    
+    // ensure power is turned on
+    LPC_SC->PCONP |= (1 << 12);
+    
+    // set PCLK of ADC to /1
+    LPC_SC->PCLKSEL0 &= ~(0x3 << 24);
+    LPC_SC->PCLKSEL0 |= (0x1 << 24);
+    uint32_t PCLK = SystemCoreClock;
+    
+    // calculate minimum clock divider
+    //  clkdiv = divider - 1
+    uint32_t MAX_ADC_CLK = 13000000;
+    uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
+    
+    // Set the generic software-controlled ADC settings
+    LPC_ADC->ADCR = (0 << 0)      // SEL: 0 = no channels selected
+                  | (clkdiv << 8) // CLKDIV: PCLK max ~= 25MHz, /25 to give safe 1MHz at fastest
+                  | (0 << 16)     // BURST: 0 = software control
+                  | (0 << 17)     // CLKS: not applicable
+                  | (1 << 21)     // PDN: 1 = operational
+                  | (0 << 24)     // START: 0 = no start
+                  | (0 << 27);    // EDGE: not applicable
+    
+    pinmap_pinout(pin, PinMap_ADC);
+}
+
+static inline uint32_t adc_read(analogin_t *obj) {
+    // Select the appropriate channel and start conversion
+    LPC_ADC->ADCR &= ~0xFF;
+    LPC_ADC->ADCR |= 1 << (int)obj->adc;
+    LPC_ADC->ADCR |= 1 << 24;
+    
+    // Repeatedly get the sample data until DONE bit
+    unsigned int data;
+    do {
+        data = LPC_ADC->ADGDR;
+    } while ((data & ((unsigned int)1 << 31)) == 0);
+    
+    // Stop conversion
+    LPC_ADC->ADCR &= ~(1 << 24);
+    
+    return (data >> 4) & ADC_RANGE; // 12 bit
+}
+
+static inline void order(uint32_t *a, uint32_t *b) {
+    if (*a > *b) {
+        uint32_t t = *a;
+        *a = *b;
+        *b = t;
+    }
+}
+
+static inline uint32_t adc_read_u32(analogin_t *obj) {
+    uint32_t value;
+#if ANALOGIN_MEDIAN_FILTER
+    uint32_t v1 = adc_read(obj);
+    uint32_t v2 = adc_read(obj);
+    uint32_t v3 = adc_read(obj);
+    order(&v1, &v2);
+    order(&v2, &v3);
+    order(&v1, &v2);
+    value = v2;
+#else
+    value = adc_read(obj);
+#endif
+    return value;
+}
+
+uint16_t analogin_read_u16(analogin_t *obj) {
+    uint32_t value = adc_read_u32(obj);
+    
+    return (value << 4) | ((value >> 8) & 0x000F); // 12 bit
+}
+
+float analogin_read(analogin_t *obj) {
+    uint32_t value = adc_read_u32(obj);
+    return (float)value * (1.0f / (float)ADC_RANGE);
+}